Double individual-addressing multi-beam raman system

ABSTRACT

Aspects of the present disclosure relate generally to systems and methods for use in the implementation and/or operation of quantum information processing (QIP) systems, and more particularly, to a double individual-addressing multi-beam Raman system for use in QIP systems. A technique is described in which a first muti-channel modulator (MCM), a first telecentric zoom lens, and a first interleaver that form a first optical path of the Raman system that receives a first array of beams and adjusts the first array of beams to individually address atomic-based qubits in a chain from a first direction. Moreover, a second MCM, a second telecentric zoom lens, and a second interleaver form a second optical path of the Raman system that receives a second array of beams and adjusts the second arrays of beams to individually address the atomic-based qubits in the chain from a second direction different from the first direction.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to and the benefit of U.S.Provisional Patent Application No. 63/287,002, entitled “DOUBLEINDIVIDUAL-ADDRESSING MULTI-BEAM RAMAN SYSTEM,” and filed on Dec. 7,2021, the contents of which are incorporated herein by reference intheir entirety.

TECHNICAL FIELD

Aspects of the present disclosure relate generally to systems andmethods for use in the implementation and/or operation of quantuminformation processing (QIP) systems, and more particularly, to a doubleindividual-addressing multi-beam Raman system for use in QIP systems.

BACKGROUND

Trapped atoms are one of the leading implementations for quantuminformation processing or quantum computing. Atomic-based qubits can beused as quantum memories, as quantum gates in quantum computers andsimulators, and can act as nodes for quantum communication networks.Qubits based on trapped atomic ions enjoy a rare combination ofattributes. For example, qubits based on trapped atomic ions have verygood coherence properties, can be prepared and measured with nearly 100%efficiency, and are readily entangled with each other by modulatingtheir Coulomb interaction with suitable external control fields such asoptical or microwave fields. These attributes make atomic-based qubitsattractive for extended quantum operations such as quantum computationsor quantum simulations.

It is therefore important to develop new techniques that improve thedesign, fabrication, implementation, and/or control of different QIPsystems used as quantum computers or quantum simulators, andparticularly for those QIP systems that handle operations based onatomic-based qubits.

SUMMARY

The following presents a simplified summary of one or more aspects toprovide a basic understanding of such aspects. This summary is not anextensive overview of all contemplated aspects and is intended toneither identify key or critical elements of all aspects nor delineatethe scope of any or all aspects. Its sole purpose is to present someconcepts of one or more aspects in a simplified form as a prelude to themore detailed description that is presented later.

This disclosure describes various aspects of a doubleindividual-addressing multi-beam Raman system for use in QIP systems.

Aspects of this disclosure describe a Raman system for doubleindividual-addressing of atomic-based qubits that includes a firstmuti-channel modulator (MCM), a first telecentric zoom lens, and a firstinterleaver that with one or more optical components form a firstoptical path of the Raman system and are configured to receive a firstarray of beams and to adjust the first array of beams for each beam inthe first array of beams to individually address a respectiveatomic-based qubit in a chain from a first direction. The Raman systemalso includes a second MCM, a second telecentric zoom lens, and a secondinterleaver that with one or more optical components form a secondoptical path of the Raman system and are configured to receive a secondarray of beams and to adjust the second arrays of beams for each beam inthe second array of beams to individually address a respectiveatomic-based qubit in the chain from a second direction different fromthe first direction. The first optical path and the second optical pathcan be symmetrical.

In an aspect of this Raman system, each beam in the first array of beamsis an elliptical beam, each beam in the second array of beams is anelliptical beam, and corresponding elliptical beams from the first arrayof beams and from the second array of beams substantially overlap. Theelliptical beams can be Gaussian beams.

In an aspect of this Raman system, the Raman system can further includea laser source and a first diffractive optical element (DOE) and asecond DOE. The laser source is configured to generate a single beam,the single beam is split and a portion is provided to the first DOE andthe first DOE is configured to generate the first array of beams fromthe portion of the single beam, and a remaining portion of single beamis provided to the second DOE and the second DOE is configured togenerate the second array of beams from the remaining portion of thesingle beam.

In an aspect of this Raman system, the first MCM is a firstmulti-channel acousto-optic modulator (AOM), and the second MCM is asecond multi-channel AOM. The channels in the first multi-channel AOMinclude one channel for each of the beams in the first array of beams,each channel in the first multi-channel AOM is configured toindependently control one or more characteristics of the respective oneof the first array of beams applied to that channel, and the channels inthe second multi-channel AOM include one channel for each of the beamsin the second set of beams, each channel in the second multi-channel AOMis configured to independently control one or more characteristics ofthe respective one of the first array of beams applied to that channel.Additionally or alternatively, the first array of beams received by thefirst optical path has a beam spacing that matches a spacing between thechannels in the first multi-channel AOM, the second array of beamsreceived by the second optical path has a beam spacing that matches aspacing between the channels in the second multi-channel AOM, the firstoptical path is configured to adjust the beam spacing of the first arrayof beams to match a spacing of the atomic-based qubits in the chain, andthe second optical path is configured to adjust the beam spacing of thesecond array of beams to match the spacing of the atomic-based qubits inthe chain. The first optical path is further configured to adjust a beamsize of the beams in the first array of beams according to an optimalsize (e.g., based on adjustability and complex metrics) of theatomic-based qubits in the chain, and the second optical path is furtherconfigured to adjust a beam size of the beams in the second array ofbeams according to the size of the atomic-based qubits in the chain.

In an aspect of this Raman system, each of the first telecentric zoomlens and the second telecentric zoom lens has an outer pair of lensesand an inner pair of lenses, the outer pair of lenses is of fixedposition and the inner pair of lenses is configured to move together toadjust an optical characteristic or the inner pair of lenses is of fixedposition and the outer pair of lenses is configured to move together toadjust the optical characteristic.

In an aspect of this Raman system the first array of beams includes afirst subset of beams and a second subset of beams, the firstinterleaver is configured to optically adjust a position the beams inthe first array of beams such that beams from the first subset of beamsand beams from the second subset of beams alternate and have a reducedbeam spacing at an output of the first interleaver, and the second arrayof beams includes a first subset of beams and a second subset of beams,the second interleaver is configured to optically adjust a position ofthe beams in the second array of beams such that beams from the firstsubset of beams and beams from the second subset of beams alternate andhave a reduced beam spacing at an output of the second interleaver. Thefirst interleaver includes a first path for the first subset of beamsfrom the first array of beams and a second path for the second subset ofbeams from the first array of beams, and the second interleaver includesa first path for the first subset of beams from the second array ofbeams and a second path for the second subset of beams from the secondarray of beams.

In an aspect of this Raman system, the first optical path is furtherformed by a first reflective dove prism, and the second optical path isfurther formed by a second reflective dove prism.

In an aspect of this Raman system, the first direction for each beam ofthe first array of beams to individually address the respectiveatomic-based qubit in the chain is opposite to the second direction foreach beam of the second array of beams to individually address therespective atomic-based qubit in the chain.

In an aspect of this Raman system, each of the atomic-based qubits inthe chain is an ion.

Aspects of this disclosure describe a method for doubleindividual-addressing of atomic-based qubits in a Raman system, themethod includes providing a first MCM, a first telecentric zoom lens,and a first interleaver that with one or more optical components form afirst optical path. The method also includes providing a second MCM, asecond telecentric zoom lens, and a second interleaver that with one ormore optical components form a second optical path. The method furtherincludes receiving, by the first optical path, a first array of beamsand adjusting, by the first optical path, the first array of beams foreach beam in the first array of beams to individually address arespective atomic-based qubit in a chain from a first direction; andreceiving, by the second optical path, a second array of beams andadjusting, by the second optical path, the second arrays of beams foreach beam in the second array of beams to individually address arespective atomic-based qubit in the chain from a second direction.

In an aspect of this method, each beam in the first array of beams is anelliptical beam, each beam in the second array of beams is an ellipticalbeam, and corresponding elliptical beams from the first array of beamsand from the second array of beams substantially overlap.

In an aspect of this method, the method further includes independentlycontrolling, in each channel of the first multi-channel MCM, one or morecharacteristics of the respective beam of the first array of beamsapplied to that channel, and independently controlling, in each channelof the second multi-channel MCM, one or more characteristics of therespective beam of the second array of beams applied to that channel.

In an aspect of this method, the method further includes adjusting, bythe first optical path, a beam spacing of the first array of beams tomatch a spacing of the atomic-based qubits in the chain; and adjusting,by the second optical path, a beam spacing of the second array of beamsto match a spacing of the atomic-based qubits in the chain.

In an aspect of this method, the first array of beams includes a firstsubset of beams and a second subset of beams, and the second array ofbeams includes a first subset of beams and a second subset of beams, themethod further includes adjusting, by the first interleaver, a positionof the beams in the first array of beams such that beams from the firstsubset of beams and beams from the second subset of beams alternate andhave a reduced beam spacing at an output of the first interleaver, andadjusting, by the second interleaver, a position of the beams in thesecond array of beams such that the beams from the first subset of beamsand beams from the second subset of beams alternate and have a reducedbeam spacing at an output of the second interleaver.

Individual aspects of the Raman system described above can be combinedto provide other contemplated implementations of the Raman system.Similarly, individual aspects of the method described above can becombined to provide other contemplated implementations of the method.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectscan be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed aspects will hereinafter be described in conjunction withthe appended drawings, provided to illustrate and not to limit thedisclosed aspects, wherein like designations denote like elements, andin which:

FIG. 1 illustrates a view of atomic ions a linear crystal or chain inaccordance with aspects of this disclosure.

FIG. 2 illustrates an example of a quantum information processing (QIP)system in accordance with aspects of this disclosure.

FIG. 3 illustrates an example of a computer device in accordance withaspects of this disclosure.

FIG. 4 illustrates an example of a traditional Raman beam geometry inaccordance with aspects of this disclosure.

FIG. 5 illustrates an example of double-individual geometry inaccordance with aspects of this disclosure.

FIG. 6 illustrates examples of crosstalk differences in accordance withaspects of this disclosure.

FIG. 7 illustrates examples of power efficiency differences inaccordance with aspects of this disclosure.

FIG. 8 illustrates examples of differences in spontaneous emission andidle errors in accordance with aspects of this disclosure.

FIG. 9 illustrates an example of a schematic of a Raman system thatprovides a double-individual addressing scheme in accordance withaspects of this disclosure.

FIGS. 10A and 10B illustrate examples of a reflective dove prism inaccordance with aspects of this disclosure.

FIG. 11 illustrates an example schematic of a simplified telecentriczoom lens for a double-individual system in accordance with aspects ofthis disclosure.

FIG. 12 illustrates a mechanical implementation of the simplifiedtelecentric zoom lens in accordance with aspects of this disclosure.

FIGS. 13A and 13B illustrate examples of a simplified view of aninterleaver functionality in accordance with aspects of this disclosure.

FIG. 14 illustrates an example of the beam and ion numbering after theinterleaver in accordance with aspects of this disclosure.

FIG. 15 illustrates a flow chart of a method for doubleindividual-addressing of atomic-based qubits in a Raman system inaccordance with aspects of this disclosure.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings or figures is intended as a description of variousconfigurations or implementations and is not intended to represent theonly configurations or implementations in which the concepts describedherein can be practiced. The detailed description includes specificdetails for the purpose of providing a thorough understanding of variousconcepts. However, it will be apparent to those skilled in the art thatthese concepts can be practiced without these specific details or withvariations of these specific details. In some instances, well knowncomponents are shown in block diagram form, while some blocks can berepresentative of one or more well-known components.

Previous designs of trapped ion quantum computers capable ofindividually addressing a large, linear array of qubits (see e.g., FIG.1 below) with Raman laser beams used optical elements, such as adiffractive optical element (DOE), to create a linear array ofindividually addressing beams that were put into a multi-channelmodulator (MCM), such as an acousto-optic modulator (AOM), forindividual manipulation of the individually addressing beams. This wasthen used in combination with a large “global” addressing laser beamthat addressed all qubits at the same time to achieve the overallrequirements of individual addressability in a trapped ion quantumcomputer. The combination of a DOE and MCM for generating individualaddressing beams is one example for individual addressability, and itcan be done in other ways. One such example is the use of individualmodulators (one per beam) that are fiber coupled and where the output ofa fiber array is used to generate the individually addressing beamarray.

Quantum gates could be targeted on a specific qubit or pairs of qubitsin a linear array or chain of qubits (e.g., ions) by turning on one ortwo AOM channels on the multi-channel AOM. Quantum gates requiring morethan two qubits can be realized by turning on more AOM channels in themulti-channel AOM. These individually addressed laser beams, whencombined with the much larger global beam, generate the desired gateoperation. This laser beam geometry has the benefit of simplicity, sincethe optics required to generate a large array of tightly focusedindividually addressed laser beams is complicated, while it is easy togenerate a single “global” beam with a wide spatial profile to hit allions in the ion trap. The individually addressed laser beams and theglobal beam can be provided from different directions (e.g., oppositedirections).

However, there can be several challenges to this laser beam geometry.For instance, the large global beam can induce idle phase errors on theentire qubit register, even qubits not involved in a particular gatebecause they are still illuminated. The global beam can also increasegate crosstalk errors, which can be challenging to mitigate in allsituations. Ultimately, the global beam can also increase thefundamental error due to spontaneous emission. This can occur on twofronts: first, if the laser intensity on a given ion is mismatchedbetween the two beams, the spontaneous emission error per gate can beincreased. Practically speaking, this can be true due to the non-uniformspatial profile of the global beam, such as a Gaussian spatial profileof finite width. Second, because the global beam illuminates non-targetqubits, that spontaneous emission error per qubit is increased becausethey are still illuminated even when idle, and the spontaneous emissionis multiplied by the size of your qubit register because increasedspontaneous emission error per qubit increases the overall error by thenumber of qubits in the register.

Because of these potential challenges, it is desirable to instead havean optical system capable of individually addressing a single qubit fromboth sides, i.e., a double set of individually addressed Raman beams.This type of beam geometry, however, has some of its own challenges. Thetwo sides need to generate beams which are very well matched in spacing,telecentricity, polarization, and spatial profile at the ion plane, andthe beam array axis needs to be matched to the multi-channel AOM axis,which needs to be matched to the ion chain axis. There can also be aneed for motorized degrees of freedom to adjust alignment in response toslow system drift.

Because the fidelity of a laser-based gate operation depends on thestability of the laser intensity and phase sampled at the ion position,tightly focused beams can increase the intensity noise due to pointingfluctuations of the beam. This noise can be reduced by reducingmechanical vibrations of the optical assembly, or by increasing the sizeof the beam to reduce the sensitivity to a given amount of pointingnoise. Unfortunately, design constraints in multi-channel AOM devicesmake it challenging to design a device which can accept an arbitrarybeam waist and spacing. The limitations implied by bulk optical elementsmeans this ratio of spacing to beam waist in the AOM device must beconserved at the ion plane; having a more tightly spaced ion chain,which is desirable for many reasons unrelated to the Raman optomechanics(e.g., reduced ion heating, reduced sensitivity to stray field drift atthe ion trap), would also require reduced beam waists and thus increasedsensitivity to alignment drift and pointing noise.

This disclosure describes a technique to mitigate the constraintsoutlined above based on the use of optical interleavers, which isdiscussed in more detail below. This disclosure also proposes the use ofcylindrical optics to increase the beam waist transverse to the ionchain axis. This has a few practical impacts. First, the gate errors dueto pointing noise along that axis are reduced. Second, one-qubit andtwo-qubit quantum gates often require applying multiple tones on the AOMsimultaneously to generate multiple laser frequency components on theion. Each frequency component will have its own pointing offset out ofthe AOM, which ideally is re-imaged to the same point at the ion plane(referred to as the geometric focus). In practice, it is difficult tomatch the geometric focus at the same position as the Gaussian focus,where each laser beam has the highest intensity and ideal optical phaseprofile. The pointing shift happens along the transverse direction, inwhich it is possible to elongate using cylindrical optics to reduce thesensitivity to this particular alignment offset. Having at least oneaxis with a larger beam waist can be used to reduce certain unwantedpolarization artifacts that appear as the beam waist approaches thewavelength of light. Finally, it allows matching the individuallyaddressing beam's transverse numerical aperture (NA) to the reducednumerical aperture available in the transverse direction due togeometric constraints of the ion trap packaging, optimizing, forexample, scattered light and clipping.

This disclosure also describes a system to generate a matched set ofindividually addressed laser beams that reduces crosstalk, utilizeslaser power more efficiently, reduces phase errors on idle qubits,reduces effect of spontaneous emission (a fundamental limit), solves fornew degrees of freedom (e.g., the use of a K-mirror or dove prism forfan alignment to ions, zoom lens), and addresses optical invariance(e.g., waist/spacing ratio is fixed) using an interleaver.

Solutions to the issues that can arise when implementing techniques fordouble individual-addressing in multi-beam Raman systems are explainedin more detail in connection with FIGS. 1-15 , with FIGS. 1-3 providinga background of the types of QIP systems or quantum computers, and morespecifically, of atomic-based QIP systems or quantum computers, in whichthese techniques are implemented.

FIG. 1 illustrates a diagram 100 that shows an example of multipleatomic ions 106 (e.g., atomic ions 106 a, 106 b, . . . , 106 c, and 106d) trapped in a linear crystal or chain 110 using a trap (the trap canbe inside a vacuum chamber as shown in FIG. 2 ). The trap can bereferred to as an ion trap. The ion trap shown can be built orfabricated on a semiconductor substrate, a dielectric substrate, or aglass die or wafer (also referred to as a glass substrate). The atomicions 106 can be provided to the trap as atomic species for ionizationand confinement into the chain 110.

In the example shown in FIG. 1 , the trap includes electrodes fortrapping or confining multiple atomic ions into the chain 110 that arelaser-cooled to be nearly at rest. The number of atomic ions (N) trappedcan be configurable and more or fewer atomic ions can be trapped. Theatomic ions can be ytterbium ions (e.g., ¹⁷¹Yb⁺ ions), for example. Theatomic ions are illuminated with laser (optical) radiation tuned to aresonance in ¹⁷¹Yb⁺ and the fluorescence of the atomic ions is imagedonto a camera or some other type of detection device. In this example,atomic ions can be separated by about 5 microns (μm) from each other,although the separation can be smaller or larger than 5 μm. Theseparation of the atomic ions is determined by a balance between theexternal confinement force and Coulomb repulsion and does not need to beuniform. Moreover, in addition to atomic ytterbium ions, neutral atoms,Rydberg atoms, different atomic ions or different species of atomic ionscan also be used. For example, barium ions can be used, includingdifferent isotopes of barium. The trap can be a linear RF Paul trap, butother types of confinement devices can also be used, including opticalconfinements. Thus, a confinement device can be based on differenttechniques and can hold ions, neutral atoms, or Rydberg atoms, forexample, with an ion trap being one example of such a confinementdevice. The ion trap can be a surface trap, for example.

The ions 106 in the chain 110 (or other forms of atomic-based qubits)can be individually address from different directions by using thetechniques described below.

FIG. 2 illustrates an example of a block diagram of a QIP system 200.The QIP system 200 can also be referred to as a quantum computingsystem, a quantum computer, a computer device, a trapped ion system, orthe like. The QIP system 200 can be part of a hybrid computing system inwhich the QIP system 200 is used to perform quantum computations andoperations and the hybrid computing system also includes a classicalcomputer to perform classical computations and operations. The quantumand classical computations and operations can interact in such a hybridsystem.

Shown in FIG. 2 is a general controller 205 configured to performvarious control operations of the QIP system 200. Instructions for thecontrol operations can be stored in memory (not shown) in the generalcontroller 205 and can be updated over time through a communicationsinterface (not shown). Although the general controller 205 is shownseparate from the QIP system 200, the general controller 205 can beintegrated with or be part of the QIP system 200. The general controller205 can include an automation and calibration controller 280 configuredto perform various calibration, testing, and automation operationsassociated with the QIP system 200. These calibration, testing, andautomation operations can involve, for example, all or part of anoptical and trap controller 220 and/or all or part of a chamber 250.

The QIP system 200 can include an algorithms component 210 that canoperate with other parts of the QIP system 200 to perform quantumalgorithms or quantum operations, including a stack or sequence ofcombinations of single qubit operations and/or multi-qubit operations(e.g., two-qubit operations) as well as extended quantum computations.As such, the algorithms component 210 can provide instructions tovarious components of the QIP system 200 (e.g., to the optical and trapcontroller 220) to enable the implementation of the quantum algorithmsor quantum operations. The algorithms component 210 can receiveinformation resulting from the implementation of the quantum algorithmsor quantum operations and can process the information and/or transferthe information to another component of the QIP system 200 or to anotherdevice for further processing.

The QIP system 200 can include the optical and trap controller 220 thatcontrols various aspects of a trap 270 in the chamber 250, including thegeneration of signals to control the trap 270, and controls theoperation of lasers and optical systems that provide optical beams thatinteract with the atoms or ions in the trap 270. Control of theoperations of laser and optical systems can include dynamically changingoperational parameters and/or configurations, including controllingpositioning using motorized mounts or holders. When used to confine ortrap ions, the trap 270 can be referred to as an ion trap. The trap 270,however, can also be used to trap neutral atoms, Rydberg atoms,different atomic ions or different species of atomic ions. The lasersand optical systems can be at least partially located in the optical andtrap controller 220 and/or in the chamber 250. For example, opticalsystems within the optical and trap controller 220 and the chamber 250can refer to optical components or optical assemblies.

The QIP system 200 can include an imaging system 230. The imaging system230 can include a high-resolution imager (e.g., CCD camera) or othertype of detection device (e.g., photomultiplier tube or PMT) formonitoring the atomic ions while they are being provided to the trap 270and/or after they have been provided to the trap 270. In an aspect, theimaging system 230 can be implemented separate from the optical and trapcontroller 220, however, the use of fluorescence to detect, identify,and label atomic ions using image processing algorithms can need to becoordinated with the optical and trap controller 220.

In addition to the components described above, the QIP system 200 caninclude a source 260 that provides atomic species (e.g., a plume or fluxof neutral atoms) to the chamber 250 having the trap 270. When atomicions are the basis of the quantum operations, that trap 270 confines theatomic species once ionized (e.g., photoionized). The trap 270 can bepart of a processor or processing portion of the QIP system 200. Thatis, the trap 270 can be considered at the core of the processingoperations of the QIP system 200 since it holds the atomic-based qubitsthat are used to perform the quantum operations or simulations. At leasta portion of the source 260 can be implemented separate from the chamber250.

It is to be understood that the various components of the QIP system 200described in FIG. 2 are described at a high-level for ease ofunderstanding. Such components can include one or more sub-components,the details of which can be provided below as needed to betterunderstand certain aspects of this disclosure.

Aspects of this disclosure can be implemented at least partially usingthe optical and trap controller 220, the imaging system 230, and/or thechamber 250 of the QIP system 200.

Referring now to FIG. 3 , an example of a computer system or device 300is illustrated. The computer device 300 can represent a single computingdevice, multiple computing devices, or a distributed computing system,for example. The computer device 300 can be configured as a quantumcomputer (e.g., a QIP system), a classical computer, or to perform acombination of quantum and classical computing functions, sometimesreferred to as hybrid functions or operations. For example, the computerdevice 300 can be used to process information using quantum algorithms,classical computer data processing operations, or a combination of both.In some instances, results from one set of operations (e.g., quantumalgorithms) are shared with another set of operations (e.g., classicalcomputer data processing). A generic example of the computer device 300implemented as a QIP system capable of performing quantum computationsand simulations is, for example, the QIP system 200 shown in FIG. 2 .

The computer device 300 can include a processor 310 for carrying outprocessing functions associated with one or more of the featuresdescribed herein. The processor 310 can include a single or multiple setof processors or multi-core processors. Moreover, the processor 310 canbe implemented as an integrated processing system and/or a distributedprocessing system. The processor 310 can include one or more centralprocessing units (CPUs) 310 a, one or more graphics processing units(GPUs) 310 b, one or more quantum processing units (QPUs) 310 c, one ormore intelligence processing units (IPUs) 310 d (e.g., artificialintelligence or AI processors), or a combination of some or all thosetypes of processors. In one aspect, the processor 310 can refer to ageneral processor of the computer device 300, which can also includeadditional processors 310 to perform more specific functions (e.g.,including functions to control the operation of the computer device300).

The computer device 300 can include a memory 320 for storinginstructions executable by the processor 310 to carry out operations.The memory 320 can also store data for processing by the processor 310and/or data resulting from processing by the processor 310. In animplementation, for example, the memory 320 can correspond to acomputer-readable storage medium that stores code or instructions toperform one or more functions or operations. Just like the processor310, the memory 320 can refer to a general memory of the computer device300, which can also include additional memories 320 to storeinstructions and/or data for more specific functions.

It is to be understood that the processor 310 and the memory 320 can beused in connection with different operations including but not limitedto computations, calculations, simulations, controls, calibrations,system management, and other operations of the computer device 300,including any methods or processes described herein.

Further, the computer device 300 can include a communications component330 that provides for establishing and maintaining communications withone or more parties utilizing hardware, software, and services. Thecommunications component 330 can also be used to carry communicationsbetween components on the computer device 300, as well as between thecomputer device 300 and external devices, such as devices located acrossa communications network and/or devices serially or locally connected tocomputer device 300. For example, the communications component 330 caninclude one or more buses, and can further include transmit chaincomponents and receive chain components associated with a transmitterand receiver, respectively, operable for interfacing with externaldevices. The communications component 330 can be used to receive updatedinformation for the operation or functionality of the computer device300.

Additionally, the computer device 300 can include a data store 340,which can be any suitable combination of hardware and/or software, whichprovides for mass storage of information, databases, and programsemployed in connection with the operation of the computer device 300and/or any methods or processes described herein. For example, the datastore 340 can be a data repository for operating system 360 (e.g.,classical OS, or quantum OS, or both). In one implementation, the datastore 340 can include the memory 320. In an implementation, theprocessor 310 can execute the operating system 360 and/or applicationsor programs, and the memory 320 or the data store 340 can store them.

The computer device 300 can also include a user interface component 350configured to receive inputs from a user of the computer device 300 andfurther configured to generate outputs for presentation to the user orto provide to a different system (directly or indirectly). The userinterface component 350 can include one or more input devices, includingbut not limited to a keyboard, a number pad, a mouse, a touch-sensitivedisplay, a digitizer, a navigation key, a function key, a microphone, avoice recognition component, any other mechanism capable of receiving aninput from a user, or any combination thereof. Further, the userinterface component 350 can include one or more output devices,including but not limited to a display, a speaker, a haptic feedbackmechanism, a printer, any other mechanism capable of presenting anoutput to a user, or any combination thereof. In an implementation, theuser interface component 350 can transmit and/or receive messagescorresponding to the operation of the operating system 360. When thecomputer device 300 is implemented as part of a cloud-basedinfrastructure solution, the user interface component 350 can be used toallow a user of the cloud-based infrastructure solution to remotelyinteract with the computer device 300.

In connection with the systems described in FIGS. 1-3 , techniques togenerate a double set of individually addressing laser beams for theatomic-based qubits in a quantum computer are described in more detailbelow.

FIG. 4 illustrates a diagram 400 that shows an example of a traditionalRaman beam geometry, which can be referred to as an individual-globalgeometry. A global beam 420 is incident upon an ion chain havingmultiple ions 406. The global beam 420 is incident from one direction,here from the top towards the ions 406. The global beam 420 is shaped insuch a way as to address the entire ion chain (thus the terminology of“global”). That is, the global beam 420 is wide enough to be incident oneach of the ions 406 (i.e., the qubits) in the ion chain. To achieveindividual addressing, a requirement for universal computation, a set ofindividual beams 410 that individually address the ions 406 in the ionchain is incident from a direction different from the direction of theglobal beam 420. In this case, the direction of the individual beams 410is from the bottom towards the ions 406. These directions (i.e., thedirection of the global beam 420 and the direction of the individualbeams 410) can be directly opposite directions or can be two differentdirections that are not exactly opposite each other or colinear.

In the diagram 400, the beams are shown based on the shape and/or size(e.g., laser beam spot shape and/or size) they have when incident on therespective ions 406. For example, N ions 406 are shown for illustrationpurposes and there are N individual beams 410, each of which has anelliptical shape when incident on its respective ion 406. The globalbeam 420, however, is elongated along the length of the ion chain to bewide enough to be incident across all of the N ions 406. Thus, theindividual beams 410 are shown to be vertically oriented ellipticalbeams and the global beam 420 is shown to be a horizontally elongatedbeam.

FIG. 5 illustrates a diagram 500 of an example of double-individualgeometry as proposed in this disclosure, where the global beam 420 inFIG. 4 is replaced by a second set of individually addressing beams. Inthis example, a first set of N individual beams 510 that individuallyaddress their respective N ions 506 (i.e., the qubits) in the ion chainis incident from one direction, which in this case is from the bottomtowards the ions 506. A second set of N individual beams 520 thatindividually address their respective N ions 506 in the ion chain isincident from another direction, which in this case is from the toptowards the ions 506. These directions (i.e., the direction of theindividual beams 510 and the direction of the individual beams 520) canbe directly opposite directions or can be two different directions thatare not exactly opposite each other or colinear.

The individual beams 510 and the individual beams 520 are shown to havean elliptical shape (e.g., laser beam spot shape) because that is theirshape when incident on its respective ion 506.

As noted above, the individual addressing beams shown in FIGS. 4 and 5can be elliptical optical beams, that is, the laser beam spot shape hasan elliptical shape. Other types of optical beams, such as circularbeams, may also be used. Therefore, whichever QIP system is used toimplement the types of geometries described in connection with FIGS. 4and 5 needs to be configured to handle elliptical optical beams.

As described above, there are several advantages to the geometry shownin FIG. 5 . Some of these advantages and techniques for implementingthese advantages will be described in more detail below in connectionswith FIGS. 6-15 .

FIG. 6 illustrates diagrams 600 and 650 that show examples of crosstalkdifferences for different geometries. The diagram 600 (left side of thefigure) shows the case for double-individual geometry (see e.g., FIG. 5) and the diagram 650 (the right side of the figure) shows the case forthe individual-global geometry (see e.g., FIG. 4 ), where thedouble-individual geometry reduces qubit crosstalk when compared to theindividual-global geometry.

In each of the diagrams in FIG. 6 , it is the center ion that is beingaddressed by individual beams. Crosstalk is proportional to the laserbeam intensity that is incident upon ions that are not being addressedby the individual beams, which in this case are the ions to the left andto the right of the center ions. In other words, if the laser intensityof the laser beams, both individual and global, intended for the centerions overlaps with adjacent ions to the left and/or to the right of thecenter ions, then the adjacent ions can receive an unintended amount oflaser intensity (crosstalk) from the individual and global beams whenaddressing the center ions.

The diagram 600 in FIG. 6 shows an example of the double-individualgeometry, with one individual beam 610 (solid line) incident on a centerion 606 b from one direction (e.g., from the back of the figure) andanother individual beam 620 (dashed line) incident on the center ion 606b from another direction (e.g., from the front of the figure). In thisexample the individual beams 610 and 620 are elliptical optical beamswith substantially the same orientation (e.g., vertical orientation),shape, and size, and are only shown to be slightly different to be ableto identify them from each other in the diagram. The individual beams610 and 620 are intended to substantially overlap (e.g., havesubstantially the same orientation, shape, and size) at the point atwhich they are both incident on the center ion 606 b. Because of thisgeometry, only a small amount of the laser intensity from both beams isincident on the neighboring ions (e.g., a left ion 606 a and a right ion606 c). That is, only a small portion of the beams used to individuallyaddress the center ion 606 b overlaps with the left ion 606 a and theright ion 606 c and thus crosstalk in those adjacent ions resulting fromaddressing the center ion is reduced or minimized.

The diagram 650 in FIG. 6 shows the traditional individual-globalgeometry, with one individual beam 660 (solid line) incident on thecenter ion 606 b from one direction (e.g., from the back of the figure)and a global beam 670 (dashed line) incident on the center ion 606 bfrom another direction (e.g., from the front of the figure). In thisexample, the individual beam 660 and the global beam 670 do not have thesubstantially the same orientation, shape, and size. For example, theindividual beam 660 is shown to be vertically oriented and the globalbeam 670, which as described above is elongated along the ion chain, isshown to have a different orientation. The individual beam 660 can be anelliptical optical beam. Because of this geometry, although only a smallamount of laser intensity from the individual beam 660 is incident inthe neighboring ions (e.g., the left ion 606 a and the right ion 606 c),as shown by the small overlap, the full intensity of the global beam 670is incident on the neighboring ions, which results in a the global beam670 overlapping the left ion 606 a and the right ion 606 c and thuscrosstalk tends to be larger than in the individual-global geometry thanin the double-individual geometry.

FIG. 7 illustrates diagrams 700 and 750 that show examples of powerefficiency differences for different geometries. The diagram 700 (e.g.,the left side of the figure) shows the case for double-individualgeometry and the diagram 750 (e.g., the right side of the figure) showsthe case for the individual-global geometry, where the double-individualgeometry is more efficient and, therefore, more scalable.

In the diagram 700 in FIG. 7 , individual beams 710 a, 710 b, and 710 c(solid lines) are respectively incident on ions 706 a, 706 b, and 706 cfrom one direction (e.g., from the back of the figure), and individualbeams 720 a, 720 b, and 720 c (dashed lines) are respectively incidenton the ions 706 a, 706 b, and 706 c from another direction (e.g., fromthe front of the figure). In this example, the individual beams 710 a,710 b, and 710 c and their corresponding individual beams 720 a, 720 b,and 720 c are elliptical optical beams with substantially the sameorientation (e.g., vertical orientation), shape, and size, and are onlyshown to be slightly different to be able to identify them from eachother in the diagram. The individual beams 710 a, 710 b, and 710 c andtheir corresponding individual beams 720 a, 720 b, and 720 c areintended to substantially overlap (e.g., have substantially the sameorientation, shape, and size) at the point at which they are incident ontheir respective ions 706 a, 706 b, and 706 c. The double-individualgeometry illustrated in the diagram 700 enables beam shaping, which canprovide optimal laser power delivery to the appropriate ion locationswithout the power being wasted between the ions or by it being appliedto the wrong ions.

In the diagram 750 in FIG. 7 , individual beams 760 a, 760 b, and 760 c(solid lines) are respectively incident on ions 706 a, 706 b, and 706 cfrom one direction (e.g., from the back of the figure), and a globalbeam 770 (dashed line) is incident on all the ions 706 a, 706 b, and 706c from another direction (e.g., from the front of the figure). In thisexample, the individual beams 760 a, 760 b, and 760 c have substantiallythe same orientation (e.g., vertical orientation), shape and size. Theglobal beam 770, however, is elongated along the ion chain, and is shownto have a different orientation, shape, and size than the individualbeams. In the diagram 750, the arrows indicate wasted power that isdelivered to the vacuum space between ions in the chain.

In an example to illustrate power efficiency differences, when theindividual beams have a beam diameter is 1.5 mm and the ion spacing is4.5 mm, the overhead on the individual-global geometry is 100%. Thus,typically the individual-global geometry may tend to be less efficientthan the double-individual geometry because less of the power is wasted.However, there may be instances in which additional losses resultingfrom generating the additional set of individual beams in thedouble-individual geometry may be such that the individual-globalgeometry may be more power efficient.

FIG. 8 illustrates diagrams 800 and 850 that show examples ofdifferences in spontaneous emission and idle errors for differentgeometries. The diagram 800 (e.g., the left side of the figure) showsthe case for double-individual geometry and the diagram 850 (e.g., theright side of the figure) shows the case for the individual-globalgeometry.

In the diagram 800 in FIG. 8 , there are shown ions 806 a, 806 b, and806 c. The center ion, ion 806 b, is addressed with an individual beam810 (solid line) from one direction (e.g., from the back of the figure),and an individual beam 820 (dashed line) from another direction (e.g.,from the front of the figure). In this example, the individual beams 810and 820 are elliptical optical beams with substantially the sameorientation (e.g., vertical orientation), shape, and size, and are onlyshown to be slightly different to be able to identify them from eachother in the diagram. The neighboring ions, the left ion 806 a and theright ion 806 c, are not addressed with individual beams.

In the diagram 850 in FIG. 8 , there are also shown the ions 806 a, 806b, and 806 c, with the center ion 806 b being addressed by an individualbeam 860 (solid line) from one direction and all the ions having aglobal beam 870 incident on them from another direction. The individualbeam 860 is an elliptical optical beam and the global beam 870 iselongated along the ion chain, and is shown to have a differentorientation, shape, and size than the individual beam 860.

Using the double-individual geometry in the diagram 800 allows for beamshaping to be implemented to help to minimize light incident on theneighboring ions. Thus, the double-individual geometry can reduce theeffects of fundamental limits on a Raman addressing system.

The individual-global geometry in the diagram 850 is where the fullintensity of the global beam 870 is incident upon all ions in the chainfor all Raman operations. This unwanted intensity can lead to what areknown as idle errors, or errors in qubits when ostensibly no operationsare being applied to them, which include unwanted shifts and spontaneousemission, which limits quantum computing fidelity and performance. Inthis example, spontaneous emission is indicated by black arrowsrepresenting photons being scattered by the neighboring ions (whichrepresent all ions in the chain). Since this error scales with thenumber of ions in the chain (e.g., the size of the quantum computer),this error is made worse as the system scales.

The double-individual geometry in the diagram 800 also allows foroptimizing the spontaneous emission from a target qubit by balancing theintensity on both sides, which optimizes the Rabi rate (interactionstrength) per unit of spontaneous emission.

FIG. 9 illustrates a diagram 500 that shows an example of adouble-individual Raman system schematic. This implementation is forillustration purposes and some variations are possible within the scopeof this disclosure.

The double-individual Rama system includes two symmetrical portions orparts, a left Raman (left half of the diagram 900) and a right Raman(right half of the diagram 900). Because the left and right halves ofthe system in the diagram 900 are symmetric, the operations andconfigurations of the two halves of the double-individual Raman systemare substantially the same.

A laser source 950 generates a laser beam that is split so that it canbe provided as input to both the left Raman and the right Raman. For theleft Raman, the input laser beam is provided to a diffractive opticalelement (DOE) 905 a that generates an array of individual laser beams.The number of beams generated by the DOE 905 a is based on the number oforders supported by the DOE (i.e., the DOE orders) and needs to besufficient to allow for individual addressing of qubits 960 (e.g., anarray of ions in an ion chain as described in FIG. 1 ). In someinstances, the DOE 905 a may generate more beams than the number ofindividual laser beams needed by the left Raman. The array of individuallaser beams is provided to a multi-channel modulator (MCM) 915 a afterpassing through an optical system 910 a that allows for the spacingbetween the individual laser beams to match the spacing of the channelsin the MCM 915 a. In an example, the MCM 915 a may be an acousto-opticmodulator (AOM) or an electro-optic modulator (EOM) and may have asufficient number of channels to separately control each of theindividual laser beams. As shown in the diagram 900, the MCM 915 areceives channel signals (e.g., channel controls) to separately controleach of the individual laser beams, including signals for controllingthe amplitude, phase, frequency, and/or polarization of each individuallaser beam.

After the MCM 915 a, the array of individual laser beams is sent throughthe remaining portion of the left Raman consisting of lenses, mirrors,and a number of beam shaping or beam configuration devices. For example,the array of individual laser beams passes through a double-telecentriczoom lens simply referred to as a telecentric zoom lens or zoom lens 920a, an interleaver 925 a, a dove prism 930 a, and another set of lenses,mirrors, and beam shaping devices or beam configuration 935 a. At theend, the array of individual laser beams is imaged onto the qubits 960.When the qubits comprise a chain of ions or other atomic-based qubits,the imaging of the array of individual laser beams is as shown in FIG. 5, for example.

The left Raman is such that the MCM 915 a, the zoom lens 920 a, and theinterleaver 925 a, along with one or more optical components, form afirst or left optical path of the overall Raman system. These componentsare configured to receive the array of individual laser beams (e.g.,from the DOE 905 a) and to adjust and/or configure the array ofindividual laser beams such that each beam in the array is used toindividually address a respective qubit in the qubits 960 (e.g., arespective ion in an ion chain).

The right Raman includes, in addition to mirrors and lenses, a DOE 905b, an optical system 910 b, an MCM 915 b, a zoom lens 920 b, aninterleaver 925 b, a dove prism 930 b, and another set of lenses,mirrors, and beam shaping or beam configuration devices 935 b. As notedabove, the right Raman and the left Raman are symmetrical and theiroperations and configurations are substantially the same. Accordingly,corresponding components or elements from both halves also havesubstantially the same operations and configurations.

The right Raman is such that the MCM 915 b, the zoom lens 920 b, and theinterleaver 925 b, along with one or more optical components, form asecond or right optical path of the overall Raman system. Thesecomponents are configured to receive the array of individual laser beams(e.g., from the DOE 905 b) and to adjust and/or configure the array ofindividual laser beams such that each beam in the array is used toindividually address a respective qubit in the qubits 960 (e.g., arespective ion in an ion chain). The array of individual laser beamsprovided by the left Raman is imaged onto the qubits 960 in onedirection and the array of individual laser beams provided by the rightRaman is imaged onto the qubits 960 in another direction. For example,the two directions can be opposite directions but need not be solimited.

Some parts of the Raman system can be generated or implemented inmultiple ways. For example, the combination of a DOE and MCM can beproduced by using instead individual fiber coupled modulators that arethen combined into a fiber array. The output of the fiber array is thenused as the source of the array of individual laser beams and would bethe input into the zoom lens.

As noted above, the left Raman and the right Raman of thedouble-individual Raman system need to generate arrays of individualbeams which that are well matched in spacing, telecentricity,polarization, and spatial profile at the ion plane. Because there is aneed to match three spacings, the two sets of individual Raman beams andthe ion chain, small imperfections in the optical system magnificationcan no longer be taken up by the ion chain alone (as is the case with aglobal Raman beam).

Accordingly, to handle the additional degrees of freedom (DOFs) neededto accomplish such a matching, this disclosure proposes the use devicesthat allow for different types of beam manipulations. One such device isa reflective dove prism, or simply referred to as a dove prism, examplesof which are the dove prisms 930 a and 930 b. Details regarding the doveprism are provided below and in, for example, U.S. Pat. No. 11,322,343titled “Optical Alignment Using Reflective Dove Prisms” and issued onMay 3, 2022, the contents of which are incorporated herein by reference.Another such device is a telecentric zoom lens, or simply a zoom lens,examples of which are the zoom lens 920 a and the zoom lens 920 b.

FIGS. 10A and 10B illustrate examples of a reflective dove prism, whichprovides the roll degree-of-freedom for the array or fan of individualbeams. FIG. 10A shows a diagram 1000 that illustrates an example ofreflective elements or structures (e.g., mirrors) to reproduce thefunctionality of a dove prism (e.g., the dove prisms 930 a and 930 b).In contrast to refractive optics, the use of reflective optics involvesa change in direction of light at an interface between two differentmedia so that the light returns into the medium from which itoriginated. In reflective optics the light need not enter the secondmedium for it to change its trajectory.

In the example in the diagram 1000, an input beam 1030 (or input image)is directed to a first reflective structure 1010 a, is reflected fromthe first reflected structure 1010 a towards a second reflective element1010 b, where it is again reflected towards a third reflective structure1010 c, where it once again is reflected in a direction of a propagationaxis 1040 of the original input beam 1030. The first reflectivestructure 1010 a and the third reflective structure 1010 c are angledwith the same tilt respect the propagation axis 1040. The secondreflective structure 1010 b is essentially used to retro reflect theinput beam 1030 onto a third dimension to create the effect of aperiscope. When the arrangement of the reflecting structures is rotatedrespect a centered pivot point 1020, the input beam 1030 is tilted bytwice the rotation angle of the overall assembly. The rotation angle canbe small, for example, the rotation angle can be less than 1 degree(1.degree.). The rotation angle can be in a positive direction (e.g., inone direction) or a negative direction (e.g., in the oppositedirection), and can range as high as 90 degrees (90.degree.) in eitherdirection. The rotation angle can be controlled with accuracy of, forexample, a tenth of a degree (0.1.degree.) or better.

Now referring to FIG. 10B, a diagram 1050 is shown that illustrates aperspective view of a system or assembly with a housing 1060 for settingor positioning the reflecting structures 1010 a, 1010 b, and 1010 c inthe diagram 1000 of FIG. 10A. The input beam 1030 (or input image) isdirected toward a first reflective structure 1010 a. For example, thehousing 1060 may have a lower portion in which the first reflectivestructure 1010 a and the third reflective structure 1010 c are set atthe right tilt or angle, and an upper portion in which the secondreflective structure 1010 b is set. The reflecting structures beingseparate but embedded into the housing 1060 may be made of differentmaterials than a material used for making the housing 1060. The housing1060 is also configured to provide a free path for the reflections totake place. It is to be understood that the housing 1060 is provided byway of illustration and many different configurations, shapes, or formfactors may be used to provide the same or similar functionality to thatof the housing 1060.

FIG. 11 illustrates a diagram 1100 that shows a possible implementationof a simplified telecentric zoom lens schematic for use in adouble-individual geometry. Examples of such a telecentric zoom lens arethe zoom lens 920 a and the zoom lens 920 b in FIG. 9 . By using atelecentric zoom lens, the appropriate spacing degree-of-freedom that isneeded for the double-individual geometry can be implemented.

The telecentric zoom lens includes two sets of lenses. An outer set oftwo lenses, lenses 1110 and 1120. The lenses 1110 and 1120 are fixed,that is, they are not configured to move or slide along the optical axis1150. The outer lens distance between the two outer lenses is thereforefixed.

Also, part of the telecentric zoom lens is an inner set of two lenses,lenses 1130 and 1140. The inner lenses 1130 and 1140 are configured tomove together, that is, they are configured to move or slide togetheralong the optical axis 1150. The inner lens distance between the twoinner lenses is also fixed. In a different implementation, the innerlenses 1130 and 1140 are configured to be fixed and the outer lenses1110 and 1120 are configured to move together.

In an aspect, each of the lenses in the outer set of two lenses may beimplemented using a single lens and each of the lenses in the inner setof the two lenses may be implemented using a compound lens. Otherimplementations of the lenses in the inner set and the outer set mayalso be used. For example, any one of the lenses in the inner set or inthe outer set may be a single lens or a compound lens as the systemdemands it.

FIG. 12 illustrates a diagram 1200 that shows an isometric view of amechanical implementation of the simplified telecentric zoom lens inFIG. 11 . The telecentric zoom lens includes a base 1210, a housing 1230attached to the base 1210 and holds the outer pair of lenses (e.g.,lenses 1110 and 1120 in FIG. 11 ) in the fixed position, and a movableportion or carriage 1240 that slides along the housing 1230 and holdsthe inner pair of lenses (e.g., lenses 1130 and 1140 in FIG. 11 ). Theslide of the carriage 1240 is a linear slide that may be manual ormotorized. The outer two lenses are held together by the housing 1230and are referenced to the rest of the optical system (e.g., therespective Raman system in FIG. 9 ).

In another implementation of the simplified telecentric zoom lens, theinner pair of lenses may be of fixed position and the outer pair oflenses is configured to move together.

One of the challenges of using the double-individual geometry describedherein is the increased sensitivity to pointing noise of the beams(e.g., noise or fluctuations in the beam pointing direction). The globalbeam geometry is such that it is insensitive to pointing due to thelarge size of the global optical beam relative to the atomic-basedqubits. Only the individual beams meaningfully suffer from pointingnoise (global beam impact is negligible), thus having adouble-individual geometry increases this by a factor of 2, which hasthe effect of a factor of √{square root over (2)} on qubit operations.One way to reduce this problem is to increase the spot size of theindividual beams. This is a fundamental tradeoff with crosstalk, and anoptimal value may be chosen as a fraction of the ion spacing, forinstance. However, the traditional MCM configuration is limited by adifferent factor: the size of the beam inside the MCM device as afraction of the channel spacing, which is then reimaged onto the ionchain.

The MCM device parameters (e.g., AOM device parameters), namely the MCMchannel spacing and the Gaussian beam size the MCM is designed tohandle, set the beam array properties at the ion chain because, with atraditional imaging system, the Gaussian and geometric beam propertiesare tied together (known as the optical invariant or etendue). As anexample, an MCM device that has a channel spacing of 450 mm and adesigned Gaussian beam size of 75 μm has a spacing-to-size ratio of 6. Atypical ion chain spacing is 4.5 μm, which means that the output beamarray optics of the Raman system need to demagnify the MCM spacing by100× (i.e., from 450 mm to 4.5 mm) to reimage the optical beams onto theion chain. This means that the optical beam size, for an ion chainspacing of 4.5 μm, is 0.75 μm (i.e., a 100× demagnifying from 75 μm). Anexample of a more favorable ratio for an ion chain separation to an ionchain beam size is 3, or, in the example given above, the exemplary beamsize is approximately 1.5 μm for an ion chain separation of 4.5 μm.

The necessary factor (e.g., factor of 2) can be achieved using aninterleaver, shown in FIGS. 13A, 13B, and 14 below. FIG. 13A shows adiagram 1300 that illustrates an example of a simplified view of theinterleaver functionality. Here, an input array of optical beams issplit into two, a left half of the optical beams represented by a dashedline and a right half of the optical beams represented by a dotted line,which are then recombined into an output array of optical beams with aninterferometer-like setup 1305 having matching path lengths on each ofthe legs or paths. It is important to note that is necessary in setupsthat use pulsed lasers and may not be a requirement for other setups,such setups that use continuous wave (CW) Raman lasers. In this example,the left half of the optical beams passes through a first path (Path 1)that includes optical elements 1315, 1320, and 1335. The right half ofthe optical beams passes through a second path (Path 2) that includesoptical elements 1325, 1330, and 1335. This effectively shifts the leftside to overlap with the right side in an interdigitated geometry. Thisleaves the Gaussian beam properties unchanged and reduces the beam arrayspacing by the appropriate factor.

A similar functionality to that provided by the interleaver in thediagram 1300 in FIG. 13A can be achieved with an interleaverconfiguration that has extra mirror, an example of which is shown in adiagram 1350 in FIG. 13B. Here again an input array of optical beams issplit into two, a left half of the optical beams represented by a dashedline and a right half of the optical beams represented by a dotted line,which are then recombined into an output array of optical beams with aninterferometer-like setup 1310 having matching path lengths on each ofthe legs or paths. In this example, the left half of the optical beamspasses through a first path (Path 1) that includes optical elements1315, 1320, and 1335. The right half of the optical beams passes througha second path (Path 2) that includes optical elements 1325, 1340, 1345,and 1335. This effectively flips the left side to overlap with the rightside in an interdigitated geometry. This leaves the Gaussian beamproperties unchanged and reduces the beam array spacing by theappropriate factor.

FIG. 14 illustrates a diagram 1400 that shows an example of thenumbering of the individual laser/optical beams being applied from oneside of the Raman system and respective ions after the interleavingprocess is performed by one of the interleavers described herein or someother interleaver configuration. In this example, the ions in the ionchain are numbered 1-32 and the laser/optical beams are labeled toindicate their DOE order −16-0. As noted above, the diagram 1400 onlyshows optical beams from one side of the Raman system as they are imagedon the ions/qubits, with a similar set of optical beams being imagedfrom the other side of the Raman system but not shown.

FIG. 15 illustrates a flow chart of a method 1500 for doubleindividual-addressing of atomic-based qubits in a Raman system.

In 1510, a first MCM, a first telecentric zoom lens, and a firstinterleaver are provide which, with one or more optical components, forma first optical path. In one example, the first optical path may referto an optical path associated with the left Raman portion of a Ramansystem as shown in FIG. 9 .

In 1520, a second MCM, a second telecentric zoom lens, and a secondinterleaver are provided which, with one or more optical components,form a second optical path. In one example, the second optical path mayrefer to an optical path associated with the right Raman portion of aRaman system as shown in FIG. 9 .

In 1530, the first optical path receives a first array of beams andadjusts or manipulates the first array of beams such that each beam inthe first array of beams individually addresses a respectiveatomic-based qubit in a chain (e.g., a respective qubit in the qubits960 in FIG. 9 ) from a first direction.

In 1540, the second optical path receives a second array of beams andadjusts or manipulates the second arrays of beams such that each beam inthe second array of beams individually addresses a respectiveatomic-based qubit in the chain from a second direction.

In an aspect of the method 1500, each beam in the first array of beamsis an elliptical beam, each beam in the second array of beams is anelliptical beam, and corresponding elliptical beams from the first arrayof beams and from the second array of beams substantially overlap.

In an aspect of the method 1500, the method 1500 further includesindependently controlling, in each channel of the first multi-channelMCM, one or more characteristics of the respective beam of the firstarray of beams applied to that channel, and independently controlling,in each channel of the second multi-channel MCM, one or morecharacteristics of the respective beam of the second array of beamsapplied to that channel.

In an aspect of the method 1500, the method 1500 further includesadjusting, by the first optical path, a beam spacing of the first arrayof beams to match a spacing of the atomic-based qubits in the chain, andadjusting, by the second optical path, a beam spacing of the secondarray of beams to match a spacing of the atomic-based qubits in thechain.

In an aspect of the method 1500, the first array of beams includes afirst subset of beams and a second subset of beams, and the second arrayof beams includes a first subset of beams and a second subset of beams,and the method 1500 further includes adjusting, by the firstinterleaver, a position of the beams in the first array of beams suchthat beams from the first subset of beams and beams from the secondsubset of beams alternate and have a reduced beam spacing at an outputof the first interleaver, and adjusting, by the second interleaver, aposition of the beams in the second array of beams such that the beamsfrom the first subset of beams and beams from the second subset of beamsalternate and have a reduced beam spacing at an output of the secondinterleaver.

The previous description of the disclosure is provided to enable aperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the common principles defined herein can beapplied to other variations without departing from the scope of thedisclosure. Furthermore, although elements of the described aspects canbe described or claimed in the singular, the plural is contemplatedunless limitation to the singular is explicitly stated. Additionally,all or a portion of any aspect can be utilized with all or a portion ofany other aspect, unless stated otherwise. Thus, the disclosure is notto be limited to the examples and designs described herein but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A Raman system for double individual-addressingof atomic-based qubits, comprising: a first muti-channel modulator(MCM), a first telecentric zoom lens, and a first interleaver that withone or more optical components form a first optical path of the Ramansystem and are configured to receive a first array of beams and toadjust the first array of beams for each beam in the first array ofbeams to individually address a respective atomic-based qubit in a chainfrom a first direction; and a second MCM, a second telecentric zoomlens, and a second interleaver that with one or more optical componentsform a second optical path of the Raman system and are configured toreceive a second array of beams and to adjust the second arrays of beamsfor each beam in the second array of beams to individually address arespective atomic-based qubit in the chain from a second directiondifferent from the first direction.
 2. The Raman system of claim 1,wherein: each beam in the first array of beams is an elliptical beam,each beam in the second array of beams is an elliptical beam, andcorresponding elliptical beams from the first array of beams and fromthe second array of beams substantially overlap.
 3. The Raman system ofclaim 2, wherein the elliptical beams are Gaussian beams.
 4. The Ramansystem of claim 1, wherein the first optical path and the second opticalpath are symmetrical.
 5. The Raman system of claim 1, furthercomprising: a laser source; and a first diffractive optical element(DOE) and a second DOE, the laser source is configured to generate asingle beam, the single beam is split and a portion is provided to thefirst DOE and the first DOE is configured to generate the first array ofbeams from the portion of the single beam, and a remaining portion ofsingle beam is provided to the second DOE and the second DOE isconfigured to generate the second array of beams from the remainingportion of the single beam.
 6. The Raman system of claim 1, wherein: thefirst MCM is a first multi-channel acousto-optic modulator (AOM), andthe second MCM is a second multi-channel AOM.
 7. The Raman system ofclaim 6, wherein: the channels in the first multi-channel AOM includeone channel for each of the beams in the first array of beams, eachchannel in the first multi-channel AOM is configured to independentlycontrol one or more characteristics of the respective one of the firstarray of beams applied to that channel, and the channels in the secondmulti-channel AOM include one channel for each of the beams in thesecond set of beams, each channel in the second multi-channel AOM isconfigured to independently control one or more characteristics of therespective one of the first array of beams applied to that channel. 8.The Raman system of claim 6, wherein: the first array of beams receivedby the first optical path has a beam spacing that matches a spacingbetween the channels in the first multi-channel AOM, the second array ofbeams received by the second optical path has a beam spacing thatmatches a spacing between the channels in the second multi-channel AOM,the first optical path is configured to adjust the beam spacing of thefirst array of beams to match a spacing of the atomic-based qubits inthe chain, and the second optical path is configured to adjust the beamspacing of the second array of beams to match the spacing of theatomic-based qubits in the chain.
 9. The Raman system of claim 8,wherein: the first optical path is further configured to adjust a beamsize of the beams in the first array of beams according to an optimalsize of the atomic-based qubits in the chain, and the second opticalpath is further configured to adjust a beam size of the beams in thesecond array of beams according to the optimal size of the atomic-basedqubits in the chain.
 10. The Raman system of claim 1, wherein each ofthe first telecentric zoom lens and the second telecentric zoom lens hasan outer pair of lenses and an inner pair of lenses, the outer pair oflenses is of fixed position and the inner pair of lenses is configuredto move together to adjust an optical characteristic or the inner pairof lenses is of fixed position and the outer pair of lenses isconfigured to move together to adjust the optical characteristic. 11.The Raman system of claim 1, wherein: the first array of beams includesa first subset of beams and a second subset of beams, the firstinterleaver is configured to optically adjust a position of the beams inthe first array of beams such that beams from the first subset of beamsand beams from the second subset of beams alternate and have a reducedbeam spacing at an output of the first interleaver, and the second arrayof beams includes a first subset of beams and a second subset of beams,the second interleaver is configured to optically adjust a position ofthe beams in the second array of beams such that beams from the firstsubset of beams and beams from the second subset of beams alternate andhave a reduced beam spacing at an output of the second interleaver. 12.The Raman system of claim 11, wherein: the first interleaver includes afirst path for the first subset of beams from the first array of beamsand a second path for the second subset of beams from the first array ofbeams, and the second interleaver includes a first path for the firstsubset of beams from the second array of beams and a second path for thesecond subset of beams from the second array of beams.
 13. The Ramansystem of claim 1, wherein: the first optical path is further formed bya first reflective dove prism, and the second optical path is furtherformed by a second reflective dove prism.
 14. The Raman system of claim1, wherein the first direction for each beam of the first array of beamsto individually address the respective atomic-based qubit in the chainis opposite to the second direction for each beam of the second array ofbeams to individually address the respective atomic-based qubit in thechain.
 15. The Raman system of claim 1, wherein each of the atomic-basedqubits in the chain is an ion.
 16. A method for doubleindividual-addressing of atomic-based qubits in a Raman system,comprising: providing a first muti-channel modulator (MCM), a firsttelecentric zoom lens, and a first interleaver that with one or moreoptical components form a first optical path, providing a second MCM, asecond telecentric zoom lens, and a second interleaver that with one ormore optical components form a second optical path, receiving, by thefirst optical path, a first array of beams and adjusting, by the firstoptical path, the first array of beams for each beam in the first arrayof beams to individually address a respective atomic-based qubit in achain from a first direction; and receiving, by the second optical path,a second array of beams and adjusting, by the second optical path, thesecond array of beams for each beam in the second array of beams toindividually address a respective atomic-based qubit in the chain from asecond direction.
 17. The method of claim 16, wherein: each beam in thefirst array of beams is an elliptical beam, each beam in the secondarray of beams is an elliptical beam, and corresponding elliptical beamsfrom the first array of beams and from the second array of beamssubstantially overlap.
 18. The method of claim 16, further comprising:independently controlling, in each channel of the first multi-channelMCM, one or more characteristics of the respective beam of the firstarray of beams applied to that channel; and independently controlling,in each channel of the second multi-channel MCM, one or morecharacteristics of the respective beam of the second array of beamsapplied to that channel.
 19. The method of claim 16, further comprising:adjusting, by the first optical path, a beam spacing of the first arrayof beams to match a spacing of the atomic-based qubits in the chain; andadjusting, by the second optical path, a beam spacing of the secondarray of beams to match a spacing of the atomic-based qubits in thechain.
 20. The method of claim 16, wherein: the first array of beamsincludes a first subset of beams and a second subset of beams, and thesecond array of beams includes a first subset of beams and a secondsubset of beams, the method further comprising: adjusting, by the firstinterleaver, a position of the beams in the first array of beams suchthat beams from the first subset of beams and beams from the secondsubset of beams alternate and have a reduced beam spacing at an outputof the first interleaver; and adjusting, by the second interleaver, aposition of the beams in the second array of beams such that the beamsfrom the first subset of beams and beams from the second subset of beamsalternate and have a reduced beam spacing at an output of the secondinterleaver.